The present invention relates to a burner and relates particularly, but not exclusively, to a burner having low NO.sub.x emission and one employing a gas swirling technique to assist with complete or substantially complete combustion.
U.S. Pat. No. 3,685,740 discloses an oxygen-fuel burner of the rocket burner type comprising a cylindrical combustion chamber having an open discharge end and a burner plate with separate oxygen and fuel ports constituting the opposite end of the chamber; the projected longitudinal axis of the oxygen ports extending in converging directions towards the longitudinal axis of the chamber but being in off-set, non-intersecting relation thereto, so that points on the respective axes that most closely approach the chamber axes define a transversely positioned plane between the burner plate and the chamber exhaust; the projected longitudinal axes of the fuel ports being substantially parallel to the chamber axes for mixing of oxygen and fuel at and beyond the plane of closest approach, and means for adjusting the longitudinal position of the burner plates on the chamber axes and thereby locating the plane of closest approach in relation to the chamber exhaust for determining the pattern of the burner discharge flame. Such a burner also includes a cooling water jacket which extends towards the tip of the burner thereby to cool said tip during operation of the burner. Whilst this burner is capable of producing a number of different flame patterns, these patterns tend to be turbulent and are therefore not suitable for certain applications. It is also noted that this burner is designed for complete mixing of the oxygen / fuel so that hot fully combusted flame gases will leave the burner. Consequently, the tip of the burner will require cooling and hence the overall burner efficiency will be reduced as part of the combustion will be lost to the cooling fluid in the cooling jacket. Additionally, this burner is comparatively noisy because of the high mixing rate and the fact that any noise will be amplified in the burner body.